You cannot say Array1 = Array2 + Array3. Rather, you'd have to build Array1
from the elements of the existing arrays. Each vector of Array1 would have
to be as large as the largest equivalent vector of the source arrays. For
example, if Array2 is 3 by 1 and Array3 is 1 by 4 then Array1 would have to
be 3 by 4. That is, if I'm following you.

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Jim Rech
Excel MVP